1. Field of the Invention
The present invention relates to semiconductor devices and, more particularly, to a raised photodetector having a channel for guiding light therethrough and a light responsive region recessed within the channel for detecting light.
2. Description of the Related Art
The development of integrated optical circuits has become the subject of increased interest in the field of telecommunications. For example, feedback control of lasers in an optical system is of paramount importance as users demand more and more reliable data transmission for a given bandwidth. However, a number of difficulties have been encountered in monitoring lasers, as the monitoring mechanism itself introduces unacceptable signal losses to the optical system.
Prior art techniques require the positioning of a beam splitter along the propagation path of light from a laser so as to divert a portion of the laser light for feedback monitoring. Beam splitters may for example be constructed of dichroic mirrors, i.e. mirrors which transmit one wavelength or a range of wavelengths and reflect the remaining wavelengths. Alternatively, they may be constructed of partially reflecting mirrors which reflect a portion of the incident light and transmit the remaining portion. In any event, such beam splitting causes the output beam from the lasers to incur signal losses that are unacceptable in optical communication applications. Furthermore, beam splitters undesirably increase the number of parts in an optical system and add to its complexity, thereby increasing the cost of the system.
Accordingly, there is a need for a compact, low-cost light detecting device for monitoring light from a laser without requiring the use of a beam splitter.